Kinetics of Extracting Magnesium from Dolomite by Aluminothermic Process in Flowing Argon

Due to its low reaction temperature, fast reaction efficiency and other advantages, the aluminothermic process is the most likely to replace the Pidgeon process, but its industrial application is limited because of its high smelting cost. To reduce the production cost and realize the continuous production of magnesium by aluminothermic process, in this work, a new method of extracting magnesium by aluminothermic process in flowing argon was proposed, and the effects of carrier gas flow, briquetting pressure, and calcium fluoride content on the reduction rate and reduction reaction kinetics were investigated. The results showed that a small amount of argon flow could make the reaction proceed quickly, too large carrier gas flow and briquetting pressure were not conducive to the reduction reaction, and the increase in calcium fluoride content could speed up the reaction. When the carrier gas flow was 0.2 m 3 ·h −1 , the briquetting pressure was 15 MPa, and the reduction time was 2 h at 1473 K, the reduction rate of magnesium oxide reached > 89%. The phase formed in the reduction slag was mainly the 12CaO·7Al 2 O 3 phase. The control step of the reduction reaction was the diffusion reaction, and its apparent activation energy was 104.42 kJ·mol −1 .